Initial Stroke Analysis

Group 29: Helena Møller (s204585), Emma Christiansen (s204543), Casper Harreby (s204558), Frederik Holmstrup (s203540), and Laura Christiansen (s204582)

Introduction

The International Stroke Trial v. 2 data

Assessing efficacy and safety of antithrombotic therapy compared to control.
Antithrombotic agents: Aspirin and subcutaneous Heparin.

Stroke and treatments

Stroke is a loss of blood to the brain
All death causes in the data are due to possibly related blood problems

Project Aim

Assessing effects of antithrombotics for stroke
Antiplatelet treatment: Aspirin
Anticoagulent treatment: Heparin
There were no conclusive studies at this time to whether this type of treatments would work

Methods

Raw data:

19435 observations with 112 variables.

01_load:

Data has been loaded and saved in a tsv-file.

02_clean:

Global syntax of NA, and Y/N for binary variables.
Global syntax for the use of numbers 1-8 as to describe causes of death.
Correction of errors made when the data was collected.
Removal of column determined to be irrelevant.
Merging of columns for easier data analysis.
Data was split and re-joined into one.

03_augment

Groups created based on different treatments, and different doses of aspirin and heparin.

# 03_augment.qmd
# Adding the different treatment groups 
data_clean_trtgroups <- data_clean_hepgroups |> 
  mutate("data_group" = case_when(
    (RXASP == "Y" & RXHEP == "L") ~ "Asp-Hep(low)",
    (RXASP == "Y" & RXHEP == "M") ~ "Asp-Hep(med)",
    (RXASP == "Y" & RXHEP == "N") ~ "Asp-Hep(No)",
    (RXASP == "N" & RXHEP == "L") ~ "Asp(No)-Hep(low)",
    (RXASP == "N" & RXHEP == "M") ~ "Asp(No)-Hep(med)",
    (RXASP == "N" & RXHEP == "N") ~ "Asp(No)-Hep(No)"
  ))

Descriptive analysis

Observations/patients: 19435
Variables: 98
Treatment groups: 6

Time of death after randomization up till 6 months

Most of the patients that die, die within the first 20 days after randomization
The treatment impact must therefore happen within the first period of time

Time of death after 20 days

Events during first 14 days are indicative of treatment side effects

Apparent relief of one cause of death has the opposite effect on another cause of death
Medication seems to cause fatal side effects
All effect sizes are relatively low

Impact of treatment on subgroups

Kaplan Meier survival curve after stroke:

Aspirin-Heparin(Low) treatment is the treatment with the overall highest survival rate
All treatments with Heparin(medium) has the lowest survival rates
Applying confidence intervals shows that none of the treatments are noticably away from the control treatments

Chi squared test of the treatment effect

Discussion

There are many conflicting data collected (e.g. date of death = 20 days, but not dead)
The study is very biased for Age, effect for Age should be removed
This study found the same as the original study, but not with an as strong effect

Conclusion

Aspirin has an overall very low positive effect on the patient survival
Herparin (Medium Dose) has an overall low negative on the patient survival
Based on this study, no treatment should be given